1. Field of the Invention
The present invention relates to the identification of specific strains of bacteria, and more particularly to the differentiation and identification of a variety of bacteria believed to play a role in dental caries formation.
2. Description of the Prior Art
Numerous studies conducted over close to sixty years, have determined that certain bacteria, and in particular the bacterium Streptococcus Mutans, are found in the oral cavity, and more particularly in association with dental surfaces, so that a linear association between the presence of this bacterium and the incidence of dental caries has evolved. Streptococcus Mutans is classified as acidogenic and is found in dental plaque, that forms on tooth surfaces, and is believed to participate in the decalcification of the tooth that results from the solubilization of the complex calcium hydroxyphosphate, known as hydroxyapatite. Thus, areas where caries formation is noted, frequently exhibit a pH in the acid range.
While studies have not conclusively established the role that the various bacteria, including Streptococcus Mutans play in caries formation, further efforts at investigation and examination of Streptococcus Mutans, have been hampered by the inability to isolate and enumerate this bacteria in samples of human dental plaque. A variety of culture media have been proposed and tested, for the purpose of selectively isolating Streptococcus Mutans, however the results obtainable with the various culture media have been inconsistent and in some instances contradictory to the initial experiments where such media were tested and disclosed for use. For example, Gold et al., (1973, Arch. Oral Biol., 18:1357-1364), proposed a selective medium utilizing Mitis-Salivarius agar with added sucrose and bacitracin (MSB), however this medium and nine others were comparatively tested by Little et al. (1977, J. Clin, Microbiol., 5:578-583), and MSB gave lower microbial counts of this organism, than other non-selective media also tested. One of the media comprised a dilute trypticase yeast extract known as MM10SB, based upon a medium described and tested by Loesche et al. (1972, Arch. Oral Biol., 17:1311), as a non-selective gross medium for a variety of oral organisms.
Additional specific media have been developed and tested, however to the same results as described above. In particular Keele et al. (1973, J. Dent. Res., 52:1054), disclose a medium utilizing plate count agar, monobasic and dibasic potassium phosphate, yeast extract, BCP indicator and 1% glucose (GAM), which in turn, was derived from a medium disclosed by Handleman et al. (1968, Arch. Oral Biol., 13:1187-1196), that had sought to specify acidogenic streptococci by the use of tryptone-glucose agar, monobasic and dibasic potassium phosphate, yeast extract and BCP indicator. Both of these media, however, while offering generally uninhibited growth, are inadequately specific to differentiate Streptococcus Mutans, to the extent necessary and desirable to permit further observation and experimentation to be made.
A need therefore exists for the development of a culture medium that is specific for differentiation of Streptococcus Mutans without inhibiting the development of full bacterial counts.